<h1 id="connecticut-congressional-districts">2010 Connecticut
Congressional Districts</h1>
<h2 id="redistricting-requirements">Redistricting requirements</h2>
<p>In Connecticut, there are no state law requirements for congressional
districts. The Supreme Court of Connecticut set out the <a
href="https://www.cga.ct.gov/red2011/documents/special_master/Merged%20Draft%20Report%20with%20Exhibits.pdf">following
guidelines</a> in the order appointing a special master. 1. Districts
shall be as equal in population as is practicable. 1. Districts shall be
made of contiguous territory. 1. Districts shall comply with 42 U.S.C. §
1973(b) and with other applicable provisions of the Voting Rights Act
and federal law. 1. Districts shall not be substantially less compact
than the existing congressional districts. 1. Districts shall not
substantially violate town lines more than the existing congressional
districts. 1. Districts shall not consider either the residency of
incumbents or potential candidates or other political data, such as
party registration statistics or election returns.</p>
<h3 id="interpretation-of-requirements">Interpretation of
requirements</h3>
<p>We enforce a maximum population deviation of 0.5%, which is in line
with the low population deviation observed in the 2000 congressional
district plan. We use a pseudo-county constraint described below which
attempts to mimic the norms in Connecticut of generally preserving
county and municipal boundaries.</p>
<h2 id="data-sources">Data Sources</h2>
<p>Data for Connecticut comes from the ALARM Project’s <a
href="https://alarm-redist.github.io/posts/2021-08-10-census-2020/">Redistricting
Data Files</a>.</p>
<h2 id="pre-processing-notes">Pre-processing Notes</h2>
<p>No manual pre-processing decisions were necessary.</p>
<h2 id="simulation-notes">Simulation Notes</h2>
<p>We sample 5,000 districting plans for Connecticut across two
independent runs of the SMC algorithm. We use a pseudo-county constraint
to limit county and municipality splits. Municipality lines are used in
Fairfield County, Hartford County, and New Haven County, which are all
counties with populations larger than 40% the target population for a
district. No special techniques were needed to produce the sample.</p>
<h2 id="contents">Contents</h2>
<ul>
<li><code>CT_cd_2010_stats.csv</code> contains summary statistics on the
sampled redistricting plans</li>
<li><code>CT_cd_2010_plans.rds</code> is a compressed
<code>redist_plans</code> object, which contains the matrix of
precinct/block assignments and may be used for further analysis.</li>
<li><code>CT_cd_2010_map.rds</code> is a compressed
<code>redist_map</code> object, which contains the precinct/block
shapefile and demographic data.</li>
</ul>
<p>Both the <code>redist_plans</code> and <code>redist_map</code> object
are intended to be used with the <a
href="https://alarm-redist.github.io/redist/">redist package</a>.</p>
<h3 id="codebook-for-summary-statistics">Codebook for summary
statistics</h3>
<ul>
<li><code>draw</code>: unique identifier for each sample. Non-numeric
draw names are real-world plans, e.g., <code>cd_2010</code> for an
enacted 2010 plan.</li>
<li><code>district</code>: a district identifier. District numbers
roughly match those in the enacted plan, but the correspondence is not
perfect.</li>
<li><code>chain</code>: a number identifying the run of the
redistricting algorithm used to produce this draw. Used for diagnostic
purposes.</li>
<li><code>pop_overlap</code>: a number indicating the fraction of people
in this plan who reside in the same-numbered district in the enacted
plan.</li>
<li><code>total_pop</code>: the total population of each district.</li>
<li><code>total_vap</code>: the total voting-aged population of each
district.</li>
<li><code>pop_*</code>, <code>vap_*</code>: total (voting-aged)
population within racial and ethnic groups for each district. Variable
codes documented <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>plan_dev</code>: the maximum population deviation among
districts in the plan. Computed as
<code>max(abs(distr_pop - target_pop)/target_pop)</code>.</li>
<li><code>comp_edge</code>: compactness, as measured by the fraction of
internal edges kept. Higher values indicate more compactness.</li>
<li><code>comp_polsby</code>: compactness, as measured by the
Polsby-Popper score. Higher values indicate more compactness.</li>
<li><code>county_splits</code>: the number of counties which belong to
more than one district.</li>
<li><code>muni_splits</code>: the number of Census Designated Places
which belong to more than one district.</li>
<li><code>*_##_dem_*</code>, <code>*_##_rep_*</code>: vote counts for
statewide Democratic and Republican candidates in a certain election.
More information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>adv_##</code>, <code>arv_##</code>: average vote counts for
statewide Democratic and Republican candidates in a certain year. More
information <a
href="https://github.com/alarm-redist/census-2020#data-format">here</a>.</li>
<li><code>ndv</code>, <code>nrv</code>: averages of the
<code>adv_##</code> and <code>arv_##</code> variables across all
available elections.</li>
<li><code>ndshare</code>: normal Democratic share, computed as
<code>ndv / (ndv + nrv)</code></li>
<li><code>e_dvs</code>: average Democratic vote share, computed as the
average of the Democratic vote share when first scored under each
statewide election.</li>
<li><code>pr_dem</code>: probability seat is represented by a Democrat;
calculated as the fraction of statewide elections under which the
district had a majority Democratic share.</li>
<li><code>e_dem</code>: expected number of Democratic seats for the
plan; equivalent to summing the <code>pr_dem</code> values across
districts</li>
<li><code>pbias</code>: partisan bias at 50% vote share, averaged across
all available elections. Positive values indicate Republican bias.</li>
<li><code>egap</code>: the efficiency gap, averaged across all available
elections. Positive values indicate Republican bias.</li>
</ul>
